write messages corresponding to action (dark or correct)

@karnem

Before, it was always written in the log file success: started correction in case of requesting dark or correction. Now it should not be the case.

Also, I corrected the path for the calibration_configuration prev. changes

webservice/messages.py

@@ -22,5 +22,7 @@ class MDC:
 class Success:
     UPLOADED_CONFIG = "SUCCESS: Uploaded config for cycle {}, proposal {}"
     START_CORRECTION = "SUCCESS: Started correction: proposal {}, run {}"
+    START_CHAR = "SUCCESS: Started dark characterization: proposal {}, run {}"
     START_CORRECTION_SIM = "SUCCESS: Started simulated correction: proposal {}, run {}"
+    START_CHAR_SIM = "SUCCESS: Started dark characterization: proposal {}, run {}"
     QUEUED = "Queued proposal {}, run {} for offline calibration"